Data Set Information
DATA_SET_NAME SPECTROPHOTOMETRY OF THE JOVIAN PLANETS AND TITAN
DATA_SET_ID ESO-J/S/N/U-SPECTROPHOTOMETER-4-V2.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION
Data Set Overview : The best description of this data set is [KARKOSCHKA1998] which can be found in ASCII form in /DOCUMENT/ICARUS98.ASC on this volume. Some of the text in this DATASET.CAT file is quoted from this reference. Additionally, the previous version (1993) of this data set is included as well. The reference for that portion of the data set is [KARKOSCHKA1994] and can be found in /DOCUMENT/ICARUS94.ASC.  Full-disk albedo spectra of the jovian planets and Titan were derived from observations at the European Southern Observatory in July 1995. The spectra extend from 300 to 1050 nm wavelength. The spectral resolution is 0.4 nm between 520 and 995 nm, and 1 nm elsewhere. The accuracy of the albedo calibration is 4 percent. UBV magnitudes were also determined. Raman scattering was quantified for each planet. Methane and ammonia bands are shown at 0.4 nm spectral resolution, including a new band at 930 nm wavelength which is probably due to ammonia. Maps of the variation of these absorptions across the disks of Jupiter and Saturn are displayed. Saturn's spectrum is undisturbed by light from its rings due to the edge-on geometry during the observations. The albedo of Uranus near 1 micro-m wavelength has dropped almost 10 percent between 1993 and 1995, while there has been no change in the ultraviolet. The signature of light from Titan's surface yielded a path length of 4 km-am of methane in Titan's atmosphere. The temperature dependence of the width of the 890-nm methane band was used to measure temperature variations at three altitude levels, resulting in the first temperature maps of Jupiter and Saturn based on reflected sunlight. Jupiter displays a banded temperature structure with some discrete features of a few Kelvin amplitude. Saturn's north-south temperature asymmetry has reversed since the Voyager observations.   Data : The tables present the methane absorption coefficient and albedos of Jupiter, Saturn, Uranus, Neptune and Titan at 1 nm resolution and 0.4 nm sampling from 300-1050 nm and at 0.4 nm resolution and 0.1 nm sampling from 520-995 nm.
DATA_SET_RELEASE_DATE 1998-09-01T00:00:00.000Z
START_TIME 1993-01-01T12:00:00.000Z
STOP_TIME 1995-01-01T12:00:00.000Z
MISSION_NAME COMET SL9/JUPITER COLLISION
GROUND BASED ATMOSPHERIC OBSERVATIONS
MISSION_START_DATE 1993-01-01T12:00:00.000Z
1993-01-01T12:00:00.000Z
MISSION_STOP_DATE 1996-01-01T12:00:00.000Z
1995-01-01T12:00:00.000Z
TARGET_NAME JUPITER
NEPTUNE
SATURN
URANUS
TITAN
TARGET_TYPE PLANET
PLANET
PLANET
PLANET
SATELLITE
INSTRUMENT_HOST_ID ESO
INSTRUMENT_NAME BOLLER & CHIVENS SPECTROGRAPH
INSTRUMENT_ID B&C
INSTRUMENT_TYPE SPECTROMETER
NODE_NAME Planetary Atmospheres
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE
Confidence Level Overview : Table II in [KARKOSCHKA1998] summarizes the UBV magnitudes, calculated from the albedo spectra by the same method as [KARKOSCHKA1994]. Note that for Jupiter, Saturn, and Titan, their full-disk albedos shown are not geometric albedos and the listed magnitudes are not opposition magnitudes due to their finite phase angles during the observation. Geometric albedos of Jupiter and Saturn are probably some 5 percent larger than the given albedos. Accordingly, their opposition magnitudes are about 0.05 more negative than the listed magnitudes.  As stated in [KARKOSCHKA1994], relative albedos are good to 2 percent and absolute albedos are good to 4 percent, mostly due to the uncertainty in the solar-to-stellar flux ratio. The 2 percent accuracy applies also to the 2-year variations which are not influenced by solar or stellar flux errors since the same comparison stars were used in both years. These percentages are relative to the albedo value, thus an albedo of 0.1 is accurate to 0.004.   Review : This data set underwent PDS peer review in January 1999. Members of the peer review panel were Lyle Huber and Ron Joyner representing PDS, Erich Karkoschka as data provider and Don Banfield and David Kuehn as external reviewers.   Data Coverage and Quality : The spectrograph has scattered light near the ends of the CCD which was not known during the observations in 1993. Thus, the albedos of 1993 below 330 nm, above 970 nm, and near 650 nm wavelength are less reliable. In 1995, this problem was known and avoided by appropriate placement. Lower levels of scattered light may be present elsewhere since they are difficult to detect. If this were the case, spectral regions with low data numbers may be influenced, which are the ends of the wavelength region, the deep methane bands, and wavelengths where the earth's atmosphere is almost opaque (cf. Fig. 1 of [KARKOSCHKA1994]). The fact that the ratios between the 1993 and 1995 data display some unexpected features of a few percent in the deepest methane bands indicates that the relative accuracy at those wavelengths may be significantly worse than the 2 percent estimate made above.  Section IV of [KARKOSCHKA1998] describes a few systematic discrepancies of about 1 percent. Many wavelength regions do not show such a discrepancy indicating that the spectral shape may have been recorded to better than the 1 % level at those wavelengths.  The indirect determination of methane absorption coefficients is likely to give more approriate values for the purpose of modeling the jovian planets' atmospheres than previous laboratory measurements at room temperature, but likely to be less reliable than recent laboratory measurements at low temperature for selected spectral regions. The levels of absorption coefficients derived here depend on Benner's values (cf. [KARKOSCHKA1994]). If some of Benner's values were wrong by 10 %, the inferred absorption coefficients could be off by 20 % in some spectral regions.
CITATION_DESCRIPTION Citation TBD
ABSTRACT_TEXT The best description of this data set can be found in [KARKOSCHKA1998]. The previous version (1993) of this data set is included as well. The reference for that portion of the data set is [KARKOSCHKA1994].
PRODUCER_FULL_NAME ERICH KARKOSCHKA
SEARCH/ACCESS DATA
  • Atmospheres Online Archives